Lattice vibrations of AVO4 crystals (A=Lu, Yb, Dy, Tb, Ce).

A short range force constant model has been applied using normal coordinates to investigate the Raman and the infrared wavenumbers in rare earth AVO4 compounds (A=Lu, Yb, Dy, Tb, Ce) having space group I41/a and symmetry C4h(6). The calculation of zone center phonons has been made by using four stretching and five bending force constants. The calculated Raman and infrared wavenumbers are in very good agreement with the observed ones. The present calculations interpret reasonably the mode assignment of 779 cm(-1) as Eg mode and 853 cm(-1) as Ag mode in case of LuVO4, which were assigned differently in earlier observation. The potential energy distribution has also been investigated for determining the significance of contribution from each force constant toward the Raman and the infrared wavenumbers.